Vehicles can be equipped to operate in both autonomous and occupant piloted mode. Vehicles can be equipped with computing devices, networks, sensors and controllers to acquire information regarding the vehicle's environment and to operate the vehicle based on the information. Safe and comfortable operation of the vehicle can depend upon determining predicted vehicle trajectories based on accurate and timely information regarding the vehicle's environment. For example, safe and comfortable operation of the vehicle can depend upon acquiring accurate and timely information regarding objects in a vehicle's environment while the vehicle is being operated on a roadway. It is a problem to provide accurate and timely information regarding objects near or around a vehicle to support operation of the vehicle.